As a process for producing a carbamate-based agricultural or horticultural bactericide, for example, there have hitherto been known (i) a process for producing a bactericide, which comprises reacting a carbamate derivative represented by the general formula (6) described hereinafter with hydroxylamine or a derivative thereof (see Preparation Method 1 of Patent Document 1); and (ii) a process for producing a bactericide, which comprises halogenating a toluene derivative to give an α-halo-substituted toluene derivative, reacting with potassium cyanate thereby to carbamate the toluene derivative, introducing a nitro group and converting the nitro group into an amino group, followed by diazotization and further reaction with an oxime compound (see Chemical Formula 11 and Preparation method 5 of Patent Document 1).
Among these methods (i) and (ii), the method (i) is considered to be preferable in the industrial preparation in view of safety because it is conducted via no diazotization, in addition to yield, safety of the reaction and ease of work and operation (see Preparation Examples 3 and 6 of Patent Document 1).
A carbamate derivative represented by the general formula (6) described hereinafter used in the method (i) is prepared by a known method, for example, a method comprising halogenating a toluene derivative having an acyl group to give an α-halo-substituted toluene derivative having an acyl group, and reacting with potassium cyanate thereby to carbamate the toluene derivative (see [Chemical Formula 8] of Patent Document 1) or a method comprising halogenating a toluene derivative having an alkoxycarbonyl group to give an α-halo-substituted toluene derivative having an alkoxycarbonyl group, reacting the toluene derivative with potassium cyanate thereby to introduce a carbamate group, and converting the alkoxycarbonyl group as a functional group into an acyl group (see [Chemical Formula 9] of Patent Document 1).
However, according to the former method described in [Chemical Formula 8] of Patent Document 1, a position isomer is produced as by-product in the preparation of a toluene derivative having an acyl group as a raw material because of low regioselectivity in case of nuclear introduction of an acyl group, and thus a decrease in yield of the objective toluene derivative having an acyl group can not be avoided. Also the latter method described in [Chemical Formula 9] of Patent Document 1 had a problem in that each step requires comparatively long time and a carbamate group itself is exposed to severe conditions in an acid or base and thus the carbamate group can not be stably maintained and is decomposed under the reaction conditions. Furthermore, it was required for any method to improve insufficient yield in entire steps from a raw material.
Patent Document 1: Japanese Unexamined Patent Publication (Kokai) No. 2001-106666
Therefore, it was required to solve the above problems of the prior art and to develop a method and a novel intermediate, which are useful for the preparation of a novel carbamate derivative.